The present invention relates to a semiconductor device and a manufacturing method therefor, and is particularly available in, for example, the manufacture of a semiconductor device having a nonvolatile memory.
As nonvolatile semiconductor memory devices capable of electrically writing and erasing, an EEPROM (Electrically Erasable and Programmable Read Only Memory) has been widely used. These memory devices typified by a flash memory widely used at present respectively have a conductive floating gate electrode or a trapping insulating film surrounded by an oxide film under a gate electrode of a MISFET, and takes a charge accumulated state at a floating gate or the trapping insulating film as memory information and reads out it as a threshold value of a transistor. The trapping insulating film refers to an insulating film capable of accumulating charges and includes a silicon nitride film or the like as one example. The trapping insulating film shifts the threshold value of the MISFET according to the injection/emission of charges into or from an area for such charge accumulation and is allowed to operate as a memory element. As the nonvolatile semiconductor memory device using the trapping insulating film, there is a split gate type cell which uses a MONOS (Metal Oxide Nitride Oxide Semiconductor) film.
There has been described in Patent Document 1 (Japanese Unexamined Patent Publication Laid-Open No. 2011-29631) that a gate electrode of a memory cell which configures a nonvolatile semiconductor memory device is configured by a two-layered film of a nondoped polysilicon layer and a metal material electrode layer.